CD-ROM Today 1996 January/CD-ROM Today 1996 January.iso/dp/0385/03856.txt

Text File | 1994-01-17 | 11.0 KB | 252 lines

$Unique_ID{BRK03856}
$Pretitle{}
$Title{Hypothyroidism}
$Subject{Hypothyroidism Myxedema Underactive Thyroid Graves Disease
Hashimoto's Thyroiditis Pendred's Syndrome }
$Volume{}
$Log{}

Copyright (C) 1988, 1989, 1990, 1992 National Organization for Rare
Disorders, Inc.

616:
Hypothyroidism

** IMPORTANT **
It is possible that the main title of the article (Hypothyroidism) is not
the name you expected.  Please check the SYNONYM listing to find the
alternate names and disorder subdivisions covered by this article.

Synonyms

     Myxedema
     Underactive Thyroid

Information on the following diseases can be found in the Related
Disorders section of this report:

     Graves Disease
     Hashimoto's Thyroiditis
     Pendred's Syndrome

General Discussion

** REMINDER **
The information contained in the Rare Disease Database is provided for
educational purposes only.  It should not be used for diagnostic or treatment
purposes.  If you wish to obtain more information about this disorder, please
contact your personal physician and/or the agencies listed in the "Resources"
section of this report.


Hypothyroidism may be a genetic or acquired condition that occurs alone
or as a symptom of another illness.  Major symptoms may include the
development of an enlarged thyroid gland (goiter) in the neck.  A dull facial
expression, puffiness and swelling around the eyes, drooping eyelids and
thinning hair, which is coarse and dry, may also occur.  Intelligence may or
may not be affected.

Symptoms

Symptoms of Hypothyroidism may result in extreme tiredness, enlargement of
the thyroid gland, poor memory, dull-witted behavior and a change in
personality.  In some cases a psychosis ("myxedema madness") may develop.
Yellowish discoloration of the skin may be seen in the hands and feet.  The
tongue can become enlarged (macroglossia) due to mucinous deposits.  A
collection of a high protein fluid around the heart may cause the heart to
become enlarged.  The lungs and abdominal spaces may also become enlarged due
to fluid accumulation.  Other signs of hypothyroidism include severe
constipation, nerve compression in the hands and feet, a lower than normal
body temperature (hypothermia) and anemia.  Infertility in men and woman may
also be caused by hypothyroidism as well as male impotence.

Hypothyroidism in the newborn is characterized by a hoarse cry,
constipation, prolonged jaundice, poor feeding, and umbilical hernias.  Bone
growth is slowed producing diagnostic findings on X-ray examination.  Early
diagnosis and treatment (less than six weeks) is critical in the newborn in
order to prevent the development of mental retardation.  Most states have
newborn screening programs to facilitate early detection and treatment.

Untreated childhood hypothyroidism is characterized by slowed growth,
delay in the development of teeth, and mental retardation.  As the child
matures the stature may be unusually short.  A rare complication of
hypothyroidism is Myxedema coma, which occurs in colder climates as a result
of lowered body temperature (hypothermia) in patients with a history of
longstanding hypothyroidism.  This can be a life-threatening consequence of
the disease in the absence of appropriate treatment.

Causes

There may be several causes of hypothyroidism.  One form of congenital
hypothyroidism is inherited as an autosomal recessive trait.  (Human traits
including the classic genetic diseases, are the product of the interaction of
two genes, one received from the father and one from the mother.  In
recessive disorders, the condition does not appear unless a person inherits
the same defective gene for the same trait from each parent.  If a person
receives one normal gene and one gene for the disease, the person will be a
carrier for the disease, but usually will show no symptoms.  The risk of
transmitting the disease to the children of a couple, both of whom are
carriers for a recessive disorder, is twenty-five percent.  Fifty percent of
their children will be carriers, but healthy as described above.  Twenty-five
percent of their children will receive both normal genes, one from each
parent, and will be genetically normal.)

Hypothyroidism may also be caused by disorders of the hypothalamus or
pituitary centers in the brain.  Other causes may be disorders that affect
control of the thyroid hormone.  Hypothyroidism may also result from blockage
in the metabolic process of transporting thyroid or iodine in the thyroid
gland itself.  Surgery or radiation to the thyroid gland may result in
hypothyroidism.  Drug therapy with propylthiouracil, methimazole, and iodides
may result in insufficient levels of useable thyroid hormone.  However, this
condition usually abates after the drug therapy is stopped.

Hypothyroidism may also be the result of an autoimmune disorder
(Hashimoto's Thyroiditis).  Autoimmune disorders are caused when the body's
natural defenses against invading organisms (i.e. antibodies, lymphocytes,
etc.), suddenly begin to attack healthy tissue.

Affected Population

Hypothyroidism affects females more often than males.  In the congenital form
it occurs once in every 3,000 births in the United States, and is not
concentrated in any particular geographic location.  It is, however, five
times more common in white infants than in black infants.  Other forms of
hypothyroidism are more common, and may occur in any age group.

Related Disorders

Symptoms of the following disorders can be similar to those of
hypothyroidism.  Comparisons may be useful for a differential diagnosis:

Graves' Disease is a rare disorder affecting the thyroid gland.  It is
thought to occur as a result of an imbalance in the endocrine system.  This
disorder causes increased thyroid secretion (hyperthyroidism), enlargement of
the thyroid gland (goiters) and protrusion of the eyeballs.  Swelling of the
legs and eyes, extreme sensitivity to light, irregular heart beat, clubbing
of the fingers, and the development of breasts in males (gynecomastia) may
also occur.  It may also cause heat intolerance, emotional instability,
weight loss or hyperactivity.  Symptoms may occur as a single incident and
then go into remission, or recurrent attacks may occur.  (For more
information on this disorder, choose "Graves'" as your search term in the
Rare Disease Database).

Hashimoto's Thyroiditis or Lymphoid Thyroiditis is the most common cause
of enlarged thyroid gland (goiter).  It is believed to be an autoimmune
disorder which can destroy the thyroid gland and produce below normal levels
of thyroid hormone secretion (hypothyroidism).  Some individuals have both
Hashimoto's Disease and Graves' Disease at the same time.  Hashimoto's
Disease can occur at any age but is most common in the third to fifth decades
of life, and is more common in women than men.  It is initially characterized
by an enlarged thyroid gland that is infiltrated with lymphocytes.
Eventually, the thyroid may be completely destroyed.  Agents which reduce
antithyroid antibody formation are the treatments of choice.  (For more
information on thia disorder, choose "Hashimoto" as your saearch term in the
Rare Disease Database.)

Pendred's Syndrome is a type of familial goiter.  Congenital nerve
deafness occurs with goiter, due to defective binding of iodine in the
thyroid.  Afflicted individuals usually have a normally functioning thyroid
gland (euthyroid).

Therapies:  Standard

Administration of the synthetic thyroid hormone, levothyroxine is the
treatment of choice for hypothyroidism.  Other treatment includes the use of
desiccated thyroid, thyroglobulin and triiodothyronine.  Surgery to remove
goiters or diseased thyroid tissue is also performed.  If the use of drugs is
responsible for the suppression of thyroid function, then the drugs may be
discontinued.  Genetic counseling is essential for families with the
inherited form of this disease.  Other treatment is symptomatic and
supportive.

The FDA has approved SmithKline Beecham's drug, Triostat (liothyronine
sodium injection) for the treatment of myxedema coma and precoma.  This drug
is the synthetic injectable form of the thyroid hormone triliodothyronine, or
T3.

Therapies:  Investigational

Clinical trials are underway to study neuropsychiatric aspects of marginal
Hypothyroidism.  Interested persons may wish to contact:

     John J. Haggerty, Jr., M.D.
     Associate Profesor
     Dept. of Psychiatry
     University of NC, Chapel Hill
     Chapel Hill, NC  27599
     [phone]

to see if further patients are needed for this research.

This disease entry is based upon medical information available through
February 1992.  Since NORD's resources are limited, it is not possible to
keep every entry in the Rare Disease Database completely current and
accurate.  Please check with the agencies listed in the Resources section for
the most current information about this disorder.

Resources

For more information on Hypothyroidism, please contact:

     National Organization for Rare Disorders (NORD)
     P.O. Box 8923
     New Fairfield, CT  06812-1783
     [phone]

     Thyroid Foundation of America
     c/o Dr. Morris Wood
     Massachusetts General Hospital
     Boston, MA 02114
     [phone]

     American Thyroid Association
     Endocrine/Metabolic Service 7D
     Walter Reed Army Medical Center
     Washington, DC  20307
     800-542-6687

     National Digestive Diseases Information Clearinghouse
     Box NDDIC
     Bethesda, MD  20892
     [phone]

For genetic information and genetic counseling referrals:

     March of Dimes Birth Defects Foundation
     1275 Mamaroneck Avenue
     White Plains, NY  10605
     [phone]

     Alliance of Genetic Support Groups
     35 Wisconsin Circle, Suite 440
     Chevy Chase, MD  20815
     (800) 336-GENE
     [phone]

References

THE METABOLIC BASIS OF INHERITED DISEASE, 5th Ed.:  John B. Stanbury, et al.,
eds.; McGraw Hill, 1983.  Pp. 231-263.

L-THYROXINE THERAPY INDUCES A FALL OF THYROID MICROSOMAL AND
THYROGLOBULIN ANITBODIES IN IDIOPATHIC MYXEDEMA AND IN HYPOTHYROID, BUT NOT
IN EUTHYROID HASHIMOTO'S THYROIDITIS.  L. Chiovato, et al.; J Endocrinol
Invest (August, 1986, issue, 9 (4)).  Pp. 299-305.

ABNORMAL TESTICULAR FUNCTION IN MEN WITH PRIMARY HYPOTHYROIDISM.  J
Wortsman, et al.; Am J Med, (February, 1987, issue 82 (2)).  Pp. 207-212.

HYPERPROLACTINEMIA, INFERTILITY, AND HYPOTHYROIDISM.  A CASE REPORT AND
LITERATURE REVIEW.  J. H. Fish, et al.; Arch Intern Med (March, 1988, issue
148 (3)).  Pp. 709-711.

CONGENITAL HYPOTHYROIDISM, INCREASED RISK OF NEONATAL MORBIDITY RESULTS
IN DELAYED TREATMENT.  P. M. Fernhoff, et al.; Lancet (February, 1987, issue 1
(8531)).  Pp. 490-491.

REPLACEMENT DOSE, METABOLISM, AND BIOAVAILABILITY OF LEVOTHYROXINE IN THE
TREATMENT OF HYPOTHYROIDISM.  ROLE OF TRIIODOTHYRONINE IN PITUITARY FEEDBACK
IN HUMANS.  L. H. Fish. et al.; N Engl J Med (March 26, 1987, issue 316 (13)).
Pp. 764-770.